Table_2_Oil and Gas Wastewater Components Alter Streambed Microbial Community Structure and Function.XLSX

The widespread application of directional drilling and hydraulic fracturing technologies expanded oil and gas (OG) development to previously inaccessible resources. A single OG well can generate millions of liters of wastewater, which is a mixture of brine produced from the fractured formations and injected hydraulic fracturing fluids (HFFs). With thousands of wells completed each year, safe management of OG wastewaters has become a major challenge to the industry and regulators. OG wastewaters are commonly disposed of by underground injection, and previous research showed that surface activities at an Underground Injection Control (UIC) facility in West Virginia affected stream biogeochemistry and sediment microbial communities immediately downstream from the facility. Because microbially driven processes can control the fate and transport of organic and inorganic components of OG wastewater, we designed a series of aerobic microcosm experiments to assess the influence of high total dissolved solids (TDS) and two common HFF additives—the biocide 2,2-dibromo-3-nitrilopropionamide (DBNPA) and ethylene glycol (an anti-scaling additive)—on microbial community structure and function. Microcosms were constructed with sediment collected upstream (background) or downstream (impacted) from the UIC facility in West Virginia. Exposure to elevated TDS resulted in a significant decrease in aerobic respiration, and microbial community analysis following incubation indicated that elevated TDS could be linked to the majority of change in community structure. Over the course of the incubation, the sediment layer in the microcosms became anoxic, and addition of DBNPA was observed to inhibit iron reduction. In general, disruptions to microbial community structure and function were more pronounced in upstream and background sediment microcosms than in impacted sediment microcosms. These results suggest that the microbial community in impacted sediments had adapted following exposure to OG wastewater releases from the site. Our findings demonstrate the potential for releases from an OG wastewater disposal facility to alter microbial communities and biogeochemical processes. We anticipate that these studies will aid in the development of useful models for the potential impact of UIC disposal facilities on adjoining surface water and shallow groundwater.

定向钻井与水力压裂技术的大规模应用，推动油气（oil and gas, OG）开发拓展至此前难以获取的资源区块。单口油气井可产生数百万升废水，这类废水由压裂地层产出的盐水与注入的水力压裂液（hydraulic fracturing fluids, HFFs）混合而成。随着每年数千口油气井投产，油气废水的安全管理已成为行业与监管机构面临的重大挑战。油气废水通常采用地下注入方式处置，既往研究显示，西弗吉尼亚州某地下注入管控（Underground Injection Control, UIC）设施的地表活动，会影响该设施下游紧邻区域的溪流生物地球化学过程与沉积物微生物群落。由于微生物驱动过程可调控油气废水中有机与无机组分的归趋与迁移行为，本研究设计了一系列有氧微宇宙实验，以评估高总溶解固体（total dissolved solids, TDS）以及两种常见水力压裂液添加剂——杀菌剂2,2-二溴-3-腈丙酰胺（DBNPA）与乙二醇（防垢剂）——对微生物群落结构与功能的影响。实验微宇宙采用取自西弗吉尼亚州该UIC设施上游（背景样点）或下游（受影响样点）的沉积物构建。暴露于高浓度总溶解固体环境会显著降低有氧呼吸速率；培养后的微生物群落分析显示，总溶解固体浓度升高与群落结构的绝大多数变化存在关联。在培养过程中，微宇宙内的沉积物层逐渐转变为厌氧环境，且观测到添加DBNPA会抑制铁还原过程。总体而言，上游背景沉积物微宇宙中，微生物群落结构与功能受到的干扰比受影响沉积物微宇宙更为显著。上述结果表明，受影响沉积物中的微生物群落，在暴露于该设施排放的油气废水后已产生适应性。本研究结果证实，油气废水处置设施的排放有潜力改变微生物群落与生物地球化学过程。我们期望本研究可为构建预测UIC处置设施对邻近地表水与浅层地下水潜在影响的实用模型提供助力。